1. Field of the Invention
This invention relates to a radio communication apparatus for performing communication using radio waves, and a method for controlling such an apparatus.
2. Description of the Related Art
Conventionally, when performing communication between radio communication apparatuses or between a radio communication apparatus and a radio-communication control apparatus, the transmission side transmits data irrespective of the state of reception processing at the reception side. When control data for temporarily interrupting the transmission of the data is received, the transmission side analyzes the control data and,temporarily interrupts the transmission of the data.
When the reception processing of the reception side starts to be delayed,because the amount of data being transmitted is too large, the reception side forms and transmits control data asking the transmission side to interrupt the transmission of the data.
The transmission side transmits a carrier for requesting data transmission a predetemined number of times before transmitting data to declare an intention of data transmission to another radio communucation terminal within the same system. By detecting the carrier indicating the declaration of intention of data transmission for the predetermined number of times, the other radio communication apparatus recognizes the presence of a radio communication apparatus intending to transmit data. Thus, communication is performed avoiding collision of transmitted data.
In the above-described conventional approach, when the reception processing of the reception side starts to be delayed, the radio communication apparatus at the reception side forms control data, which is transmitted to the radio communication apparatus at the transmission side after superimposing the control data on the carrier. Hence, time is required for that processing, and the reception processing is further delayed.
Furthermore, since the radio communication apparatus at the transmission side interrupts data transmission after analyzing the control data, the response for interrupting data transmission after receiving the control data is slow.
In addition, as for the carrier for requesting data transmission in order to avoid collision of data transmitted from the radio communication apparatus of the transmission side, the reception side cannot determine whether the received signal is the carrier for the request of data transmission or surrounding noise until the carrier is received the predetermined number of times. Hence, a time is required until the carrier for the request of data transmission is detected.